New activating groups for poly(aryl ether) synthesis

Abstract

AbstractWe have investigated new activating groups for poly(aryl ether) synthesis and have demonstrated that quinoxaline, benzazole, amide, and perfluoroalkyl groups activate fluoro‐ and, in some cases, nitro‐displacements from aromatic rings. The quinoxaline‐activated aryl ether synthesis involved activation by the electron deficient pyrazine ring of the 6‐position on the fused benzo ring. Thiophenoxides displaced 6‐chloro and 6‐nitro groups from quinoxalines under milder conditions than required for the ether synthesis. Pendent benzoxazole, benzothiazole, and amide groups activated displacement of a para fluoro group in high yield and selectivity. Perfluoroalkyl groups activated 2‐ and 4‐fluoro or nitro groups towards displacement, presumably by stabilization of the transition state through hyperconjugation. The new transformations were utilized for the synthesis of high molecular weight heterocyclic, amide and perfluoroalkyl‐based poly(aryl ethers). The resulting polymers were amorphous and displayed distinct glass transition temperatures, as well as improved solution and melt processability.